Percussion fuse of high sensitivity



Jan. 23, 1934. E w. BRANDT PERCUSSION FUSE OF HIGH SENSITIVITY FiledNov. 12, 1952 4 Sheets-Sheet 1 4 Sheets-Sheet 2 E. W. BRANDT PERCUSSIONFUSE OF HIGH SENSITIVITY Filed Nov. 12, 1932 1E ll Jan. 23, 1934.

Jan. 23, 1934.

E. W. BRANDT PERCUSSION FUSE OF HIGH SENSITIVITY Filed NOV. 12, 1932 4Sheets-Sheet S Jan. 23, 1934. E. w. BRANDT PERCUSSION FUSE OF HIGHSENSITIVITY 4 Sheets-Sheet 4 Filed Nov. 12, 1932 Patented Jan. 23, 1934Application November 12, 1932, Serial No. 642,443, and in FranceNovember 30, 1931 9 Claims.

The present invention relates to a percussion fuse of high sensitivitywhich is capable of being employed with projectiles of various types,whether discharged from smooth-bore barrels or from rifled barrels.

It more particularly proposes a fuse of this type in which the number ofindividual pieces is reduced to a minimum, and which has especially theadvantage of an absolute safety against premature percussion resultingfrom encounter with an accidental obstacle either within the barrel, orat its mouth, or even at a certain distance from the barrel.

This type of fuse, having a primer holder capable of slidinglongitudinally in an axial recess which opens, adjacent a firing pin,into an annular space of larger diameter, is remarkable especially inthat one or more locking elements located in lateral recesses of theprimer holder, are retained by the walls of the cavity in such fashionas to form a safety screen above the primer, these locking elements onlybeing able to escape laterally, for permitting percussion, at the momentwhen the primer holder penetrates into the annular space of largerdiameter.

According to another characteristic of this invention, the primer holderis normally held against movement by means of a safety device which iseliminated at the moment of firing.

Further, the primer holder is disposed in such manner as to be movedforward by inertia, by reason of the deceleration impressed upon theprojectile byair resistance; its movement being, however, pneumaticallybraked by the air which may only escape gradually from the front towardthe rear between the walls of the primer holder and the walls of itscavity.

Further advantages and details of the invention will appear from thefollowing description.

On the accompanying drawings, given only by way of example:

Figure 1 is an axial section of a fuse according to this invention,shown in the state of rest.

Figures 2 to 4 are similar views showing, respectively, the positionstaken by the parts at the moment of firing, during the safety distancefrom the mouth of the weapon, and beyond this distance.

Figures 5 and 6 show, respectively, the positions of the parts in caseof sudden braking or retardation in the barrel and in case of prematureimpact during the safety distance.

Figures 7 and 8 represent, respectively, the fuse at the moment ofimpact, by simple driving back, and of impact by driving back andinertia.

Figure 9 shows a detail in elevation.

Figure 10 is a section on line 1010 of Figure 5.

Figure 11 is a transverse section on line 1111 of Figure 7.

Figures 12 and 13 are analogous views of a modified form showing,respectively, the positions occupied by the parts while at rest and atim- 5 pact.

According to the form of execution represented in Figures 1 to 11, thefuse comprises a body 1, pierced by a drilled or bored hole 2, in whichmay slide a very light striker or firing pin 3 which is urged forward bya spring 4. This spring is supported at the rear by a flanged washer 5which surrounds a tubular element 6 that rests on the bottom of the hole2. The washer 5 assists in guiding the firing pin 3. The forward portionof the element 6 is hollowed internally and provides just below thefiring pin 3 an annular space '7 of greater diameter than the rest ofits internal bore. The element 6 can slide in the hole 2 in which it isperfectly guided by a ring 8 and by the washer 5.

A primer holder 9, enclosing a primer 10, is disposed in the tubularelement 6, within which it can slide longitudinally. Locking or distanceelements such as the balls 11 are disposed above the primer 10 inperforations 12 provided in the walls of the primer holder, and opposethe' passage of the firing pin 3, while the channels 12 are opposite thesmall diameter of the bore hole in the element 6. The diameter of balls13 is preferably greater than the thickness of the wall of the primerholder augmented by the side clearances between the primer holder andthe tubular element 6 on one side and the firing pin 3 on the otherside. The perforations or channels 12 are preferably obliquely directedto the longitudinal axis of the fuse body as shown in the drawings.

The primer holder itself is, prior to any functioning of the fuse,locked in a safety position by aid of a suitable safety device. In thepresent example, this safety device is constituted by a set of balls 13which are disposed in cavities 14. (Figs. 1 and 9). A groove 15, whichis capable of receiving the balls, extends over the external peripheryof the element 6, at the point of the cavities 14.

When the functioning of the fuse has not been initiated, the balls 13are normally retained in locking position for the primer holder by asleeve 16 which is urged forward by a spring 17 bearing rearwardsagainst ring 8. An abutment 18 limits the displacement of the ringtoward the front with respect to the element 6.

A closing ring 19, mounted in the fuse body in front of the firing pin3, preferably assures the water tightness of the fuse.

The operation is as follows:

At the moment of firing, under the prolonged action of the positiveacceleration impressed on the projectile by the propulsive charge, thefiring pin 3 and the sleeve 16 are displaced by inertia and compresstheir respective springs 4 and 1'7; the balls 13 are liberated andescape into the groove 15 (Fig. 2). After the cessation of this positiveacceleration, the spring 4 returns the firing pin into its initialposition (Fig. 3) and the sleeve 16, pressed by the spring 17, blocksthe balls 13 in the groove 15 and prevents their inward movement.

When the velocity of the projectile is being slowed down by reason ofthe air resistance (negative acceleration), the primer holder movesforward in the tubular element 6 by inertia, and finally comes to occupythe position of Fig. 4. The balls 11, located around the primer holderfrom point to point, find an annular space of greater diameter than thatin the lower portion of the tubular element 6, and can move radiallyaway from the firing pin and permit it free passage toward the primer.From this moment, the fuse is armed.

However it is proper to remark that the primer holder requires a certainlength of time for moving forward by inertia under the effect of thenegative acceleration of the projectile body, from the position ofFigure 2 into that of Figure 4; further this displacement provokes thepassage, to the rear face of the primer holder, of a part of the airwhich was originally present at the front face of this holder. This fiowof air, which may only occur gradually by reason of the small play leftbetween the walls of the primer holder and the walls of the tubularelement 6, constitutes a resistance which determines the time ofretardation, for arming, and which may be modified by the particularconstruction of these two elements.

This length of time corresponds to a safety distance for the extent ofwhich the fuse remains inert. In effect, in this space:

1. An encounter with an accidental obstacle of suflicient consistency toprovoke at the same time a driving back of the firing pin and a certaindeceleration of the projectile will occasion, by inertia, thedisplacement of the primer holder toward the front of the tubularelement 6 (Fig. 6), but the balls 11, maintained in safety position bythe walls of this tubular element, will absolutely prevent the contactof the firing pin and the primer.

2. A sudden braking, occurring accidentally in the gun barrel, willcause, by inertia, a projection of all the elements toward the front(Fig. 5) However, even in this case, the balls 11 are retainedinterposed between the firing pin and the primer, and will render anypercussion impossible.

Safety at the mouth and safety within the barrel are thus attained in apositive manner in all cases.

At impact, the percussion may be effected either by driving back of thefiring pin (Fig. 7), or by forward movement of the primer holder byinertia, or by driving back and inertia (Fig. 8).

In the first case, the primer holder is precipitated with a velocitysubstantially equal to that of the projectile onto the firing pin whichhas been abruptly arrested on the target. The balls remain in contactwith the primer holder and thus prevent any possible rearward movementof the latter on being encountered by the firing In the second case,which may occur if the projectile alone come into contact with thetarget, the tubular element 6 and the balls 13 and the sleeve 16 underthe effect of the high negative acceleration to which the projectile issubjected then add their mass to that of the primer holder forovercoming the spring 4, and thus permit the primer holder toprecipitate itself onto the firing pin.

Finally, in a case where the firing pin encounters an obstacle ofinsuflicient resistance to drive it fully backward, yet the percussionis obtained under the combined effect of the partial driving back of thefiring pin and of the inertia of the primer holder (Fig. 8).

The functioning of the fuse is very sensitive and an obstacle of veryslight mass is sufficient to actuate it. This sensitivity is attained onthe one hand by reason of the extreme lightness of the firing pin, andon the other hand by the absence of any safety element (pin, diaphragm,etc.) capable of opposing, at the moment of impact, the driving back ofthe firing pin.

V In case of a fall of the projectile during trans.- portation andhandling, no percussion may be produced, since:

The sleeve 16 will maintain, in a positive manner, the balls 13 insafety position in case of a fall of a projectile on its head or nose.

The sleeve 16 will simply compress its spring without uncovering theopenings for the escape of balls 13, in case of a fall of projectile'onits base; and even if the projectile is dropped from a height sufiicientto permit the sleeve 16 to come, under the effect of shock, to thebottom of its movement, its spring 17 will return it into the lockingposition before the balls 13 will have time to assume an appreciabledisplacement in their cavities.

The safety is thus complete in all cases.

The fuse according to this invention is, preferably, combined with adevice permitting obtaining, at will, the firing of the detonator eitherinstantaneously or with delay. In the present example, this devicecomprises two passages20, 21 (Fig. 1) traversing the base 22 of the fuseand capable of establishing communication between the primer 10 and thedetonator 23-- In one of these passages (20) is mounted a retardingcomposition 24 and, in the other, a valve 25 which may be actuateddirectly from. the exterior. When the valve is in the open position(Fig. 1) the flame from the primer 10 is transmitted directly by passage21 to the detonator 23 (instantaneous operation); when the valve is inclosed position (Fig. 2), the primer first ignites the composition 24which burns fora certain length of time and thereafter transmits thefire to the detonator (delay operation).

Figures 12 and 13 show a modification of construction of the fuseaccording to this invention. In this examplethe primer holder 9 slidesin a hole 2 of the fuse body itself. The locking sleeve 16 for the ballor balls 13 is mounted within the primer holder and is urged forwardlyby its spring 1'7 which bears, at the rear, on a ring 30 fixed to theprimer holder. The balls 13 are lodged. in channels 14: of the primerholder,

which are preferably inclined rearwardly toward the axis. Screws 31 oranalogous elements are mounted in perforations of the fuse body andpermit placing the balls 13, during assembly, in

position for blocking the primer holder.

A cup 33 rests on a shoulder 34 of the fuse body and serves as arearward support for the spring 4 of the firing pin and can itself slideforwardly in the fuse body 1.

At the moment of firing, under the effect of the continuous positiveacceleration impressed on the projectile by the propulsive charge, thesleeve lfi is moved out of the way and liberates the ball or balls 18which escape to the interior of the primer holder. The latter, beingthus unlocked moves forward in the hole 2 and carries the ball or balls13 with it, these being locked by the spring 17 (Fig. 12), and thefunctioning of this fuse is thereafter in all ways similar to that ofthe preceding example. The position of the elements at impact, with thedriving back of the firing pin is represented in Figure 13. The fuse,mounted on a rotative projectile, will operate in a manner identicalwith that which has just been indicated; the conditions for safetyremain the same.

The simplicity of its construction permits manufacturing it even of verysmall dimensions and, consequently, of using it, if desired, for thepriming of projectiles of very small calibre.

Naturally the invention is not limited to the forms of constructionshown and described, as these have only been chosen by way of examples.

Having thus described the invention, what I claim as new and desire tosecure by Letters Patent, is:-

l. A direct-action percussion fuse comprising a body having an axiallydirected elongated cavity, said cavity opening out adjacent its forwardend into an enlarged space, a striker adapted to be pushed backwardthrough and beyond said enlarged space into said cavity by an obstacle,a primer, 2. primer holder movable axially in the cavity, a releasablesafety device for locking said primer holder adjacent the backward endof the cavity, distance elements carried by the primer holder andretained by the wall of the cavity in an inward position where theyscreen the primer against impact of the striker, the primer holder beingfree after firing to creep forward in the cavity by inertia when theprojectile is being retarded air resistance and thus reach the enlargedspace into which the distance elements can escape outwardly forunscreening the primer thus arming the fuse.

2. A direct-action percussion fuse comprising a body having an axiallydirected elongated cavity, said cavity opening out adjacent its for wardend into an enlarged space, a striker adapted to be pushed backwardthrough and beyond said enlarged space into said cavity by an obstacle,a primer, a primer holder closely fitting and movable axially in thecavity, a releasable safety device for locking said primer holderadjacent the backward end of the cavity, distance elements carried bythe primer holder and retained by the wall of the cavity in an inwardposition where they screen the primer against impact of the striker, theprimer holder being free after firing to creep forward in the cavity byinertia when the projectile is being retarded by air resistance and thusreach the enlarged space into which the distance elements can escapeoutwardly for unscreening the primer thus arming the fuse, the clearancebetween the primer holder and the wall of the cavity being such that theair in the cavity can flow but gradually towards the rear end of theprimer holder whereby to brake its forward movement.

3. A direct-action percussion fuse comprising a body having an axiallydirected elongated cavity, said cavity opening out adjacent its forwardend into an enlarged space, a striker adapted to be pushed backwardthrough and beyond said enlarged space into said cavity by an obstacle,a primer, a primer holder movable axially in the cavity, a releasablesafety device for locking said primer holder adjacent the backward endof said cavity, distance balls lodged in holes of the primer holder andretained by the wall of the cavity in an inward position where theyscreen the primer against impact of the striker, the primer holder beingfree after firing to creep forward in the cavity by inertia when theprojectile is being retarded by air resistance and thus reach theenlarged space into which the distance balls can escape outwardly forunscreening the primer thus arming the fuse.

4. A direct-action percussion fuse comprising a body having an axiallydirected elongated cavity, said cavity opening out adjacent its forwardend into an enlarged space, a striker adapted to be pushed backwardthrough and beyond said enlarged space into said cavity by an obstacle,a primer, a primer holder movable in the cavity, a releasable safetydevice for locking said primer holder adjacent the backward end of saidcavity, distance balls lodged in holes of the primer holder, said holesbeing obliquely directed forwardly and outwardly with respect tothe'lon'gitudinal axis of the fuse body, said balls being retamed by thewall of the cavity in an inward position where they screen the primeragainst impact of the striker, the primer holder being free after firingto creep forward in the cavity'by inertia when the projectile is beingretarded by air resistance and thus reach the enlarged space into whichthe distance balls can escape outwardly for unscrecning the primer thusarming the fuse.

5. A direct-action percussion fuse comprising a body having an axiallydirected elongated cavity, said cavity opening out adjacent its forwardend into an enlarged space, a striker adapted to be pushed backwardthrough and beyondsai'd enlarged space into said cavity by an obstacle,a primer, a primer holder movable axially in the cavity, said primerholder having a tubular forward part, a releasable safety device forlocking said primer holder adjacent the backward end of the cavity,distance balls lodged in holes of the primer holder, the diameter ofsaid balls being greater than the thickness of the tubular part of theprimer holder augmented by the clearances between the primer holder andthe cavity, on one side and the striker on the other side, said ballsbeing retained by the wall of the cavity in an inward position wherethey screen the primer against impact of the striker, the primer holderbeing free after firing to creep forward in the cavity by inertia whenthe projectile is being retarded by air resistance and thus reach theenlarged space into which the distance balls can escape outwardly forunscreening the primer thus arming the fuse.

6. A direct-action percussion fuse comprising a fixed structure havingan axially directed elongated passage, a tube movable axially in thepassage and having an axial cavity which is narrow toward the rearwardend and has an enlargement adjacent the forward end, a springconstraining said tube in the opposite direction to the direction oftravel of said projectile, a striker adapted to be pushed backwardthrough and beyond said enlargement into the narrow portion of said tubeby an obstacle, a primer, a primer holder movable axially in the tube, areleasable safety device for locking said primer holder adjacent thebackward end of the tube, distance elements carried by the primer holderand retained by the wall of the tube in an inward position where theyscreen the primer against impact of the striker, the primer holder beingfree after firing to creep forward in the tube by inertia when theprojectile is being retarded by air resistance and thus reach theenlarged space into which the distance elements can escape outwardly forunscreening the primer thus arming the fuse, the tube being free afterfiring to move forward against the spring by inertia and bring itsnarrower part opposite the striker, so that the striker will preventsaid distance elements reaching the enlargements and thus the distanceelements will be retained in safe position and percussion prevented inthe case of a sudden deceleration being imparted to the projectilebefore the primer holder has reached the enlargement.

'7. A direct-action percussion fuse comprising a fixed structure havingan axially directed elongated passage, a tube movable axially in thepassage and having an axial cavity which is narrow toward the rearwardend and has an enlargement adjacent the forward end, a striker adaptedto be pushed backward through and beyond said enlargement into thenarrow portion of said tube by an obstacle, a spring interposed betweensaid tube and said striker, a primer, a primer holder movable in thetube, a releasable safety device for locking said primer holder adjacentthe backward end of the tube, distance elements carried by the primerholder and retained by the wall of the tube in an inward position wherethey screen the primer against impact of the striker, the primer holderbeing free after firing to creep forward in the tube by inertia when theprojectile is being retarded by air resistance and thus reach theenlarged space into which the distance elements can escape outwardly forunscreening the primer thus arming the fuse, the tube being free afterfiring to move forward against the spring by inertia and bring itsnarrower part opposite with the striker, so that the striker willprevent said distance elements reaching the enlargements and thus thedistance-elements will be retained in safe position and percussionprevented in the case of a deceleration being imparted to the projectilebefore the primer holder has reached the enlargement.

8. A direct-action percussion fuse comprising a fixed structure havingan axially directed elongated passage, a tube movable axially in thepassage and having an axial cavity which is narrow toward the rearwardend and has an enlargement adjacent the forward end, a springconstraining said tube in the opposite direction to the direction oftravel of said projectile, a striker adapted to be pushed backwardthrough and beyond said enlargement into the narrow portion of said tubeby an obstacle, a primer, a primer holder movable axially in the tube,said tube having a perforation in its wall and a peripheral groovecommunicating with said perforation, and a ball located in saidperforation and extending into the path of the primer holder while insafety position adjacent the backward end of the tube, a sleevesurrounding said tube, a setting spring constraining said sleeveforwardly for holding the ball in safety position, said sleeve beingyieldable at firing to permit the escape of said ball into said groovewhereby the primer holder is freed for movement into firing position,said setting spring also operating for returning said sleeve intoforward position after the positive acceleration for blocking said ballin said groove, distance elements carried by the primer holder andretained by the wall of the tube in an inward position where they screenthe primer against impact of the striker, the primer holder beingadapted to creep forward in the tube by inertia on the projectile beingretarded by air resistance and thus reach the enlarged space where thedistance elements can escape outwardly for unscreening the primer thusarming the fuse, said tube being free after firing to move forwardagainst the spring by inertia and bring its narrower part opposite thestriker, so that the striker will prevent said distance elementsreaching the enlargements and thus the distance elements will beretained in safe position and percussion prevented in the case of asudden deceleration being imparted to the projectile before the primerholder has reached the enlargement.

9. A direct-action percussion fuse as in claim 8, wherin the settingspring bears rearwardly against an abutment on the said tube.

EDGAR WILLIAM BRANDT.

